1. Field of the Invention
The present invention relates to a reticle which is capable of measuring a setting error of the blind of a stepper, and to a method for measuring blind setting accuracy.
2. Description of the Prior Art
In general, in contact printing, a mask is in contact with a photoresist layer, which causes the mask to become defective by repeatedly using the mask.
A projection printing is usually used to solve the problem. The projection printing can be used repeatedly without damaging the mask because the mask is not in contact with the photoresist layer.
In the projection printing, the mask may include a plurality of discrete circuits, or may include only a partial circuit of a configuration. In the case where the mask includes only a partial circuit, an image of the pattern formed on the mask is transmitted to the wafer by the step-and-repeat process of the stepper. In that case, the mask is called a reticle and, a blind is usually used to shield exposing light on a predetermined portion of the wafer. In that case, a reticle capable of measuring the blind setting accuracy is desired in order to detect an error caused by the difference between the blind and the pattern on the mask.
Referring to FIG. 1, a conventional reticle for measuring a blind setting accuracy will be described. FIG. 1 is a plan view illustrating the reticle having conventional verniers to measure a setting error of the blind of a stepper.
As shown in FIG. 1, a plurality of linear chrome patterns 2, which are square-shaped, are formed on a quartz substrate 1. Two or three verniers 3 are formed on each of the sides of the square-shaped patterns. The length of the sides of square-shaped patterns are typically 5 mm, 10 mm or 15 mm.
However, the conventional reticle for measuring the blind setting accuracy requires detecting every vernier, which has the problem of low production efficiency and the like.